http://en.wikipedia.org/wiki/The_Conference_of_the_Birds
The Conference of the Birds (Persian: منطق الطیر, Mantiqu 't-Tayr, 1177)
- It was in China, late one moonless night,
- The Simorgh first appeared to mortal sight -
- He let a feather float down through the air,
- And rumours of its fame spread everywhere;
- ...
- Come you lost Atoms to your Centre draw,
- And be the Eternal Mirror that you saw:
- Rays that have wander'd into Darkness wide
- Return and back into your Sun subside
Sulamith Wülfing (January 11, 1901 – 1989)
http://wulfing.artpassions.net/
http://en.wikipedia.org/wiki/Zodiacal_light
Zodiacal light is a faint, roughly triangular, whitish glow seen in the night sky which appears to extend up from the vicinity of the sun along the ecliptic or zodiac. Caused by sunlight scattered by space dust in the zodiacal cloud, it is so faint that either moonlight or light pollution renders it invisible. The zodiacal light decreases in intensity with distance from the Sun, but on very dark nights it has been observed in a band completely around the ecliptic. In fact, the zodiacal light covers the entire sky, being responsible for 60% of the total skylight on a moonless night. There is also a very faint, but still slightly increased, oval glow directly opposite the Sun which is known as the gegenschein.
Zodiacal light is produced by sunlight reflecting off dust particles in the solar system known as cosmic dust. Consequently, its spectrum is the same as the solar spectrum. The material producing the zodiacal light is located in a lens-shaped volume of space centered on the sun and extending well out beyond the orbit of Earth. This material is known as the interplanetary dust cloud. Since most of the material is located near the plane of the solar system, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is amazingly small. If it were in the form of 1 mm particles, each with the same albedo (reflecting power) as Earth's moon, each particle would be 8 km from its neighbors. The gegenschein may be because particles directly opposite the sun as seen from Earth would be in full phase.
The Poynting-Robertson effect causes the particles to spiral slowly into the Sun, thus requiring a continuous source of new particles to maintain the zodiacal cloud.
